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RIP: Hans Camenzind, Inventor Of The 555 Timer

A Texas Instruments 555 chip.

You may not know his name, but you've encountered Hans Camenzind's designs countless times. Hans was one of the rock stars of the integrated design world, with 20 US patents to his name and over 140 integrated circuits under his belt. He passed away on August 8th, 2012 at the age of 78, leaving the world a much buzzier and blinkier place.

He was also one of the first independent semiconductor designers, famed for hitting a home run with his first solo design–the 555 timer chip that has been incorporated into countless inexpensive electronic devices.

Incredibly, over one billion 555 timer chips are sold each year. It's a simple little 10 cent device that makes it possible to build devices that flash, buzz or turn on and off at variable intervals. Incredibly, he created the chip alone, spending a year designing it by hand as a freelancer.

Hans R. CamenzindIn the early 1970s, Camenzind was working as a design engineer for Signetics. The company hit a rough patch and started losing money, and he responded to the downturn by taking a leave of absence to write a book. While away, he decided that he didn't want to return as an employee, and proposed the 555 timer chip as a freelance project.

Because of the downturn, the company had equipment to spare which they loaned him, and in the summer of 1970 they contracted him for a year at $1200 per month (about 2/3 of his former salary). It was an unusual arrangement in those days and a huge gamble for Camenzind, who had a wife and kids to feed.

However, he had a really clever idea. His previous work involved phase locked loops (PLLs)- circuits used to lock radio equipment to precise frequencies. A PLL requires a variable oscillator, which got Camenzind thinking–he knew there would be a market for an oscillator with an integrated timer that you could trigger and then let run for a set length of time. Such circuits existed, of course, but they required dozens of discrete components.

The idea was met with enthusiasm from Signetics' marketing manager Art Fury, who had a gut feeling that it would sell well. In those days, gut feelings were often good enough.

555 block diagram

And so Camenzind set out to build the 555 IC. His design incorporated 23 transistors, 15 resistors and a pair of diodes. It would take a year to go from initial design to the production prototype stage. At the time, circuits were created by carefully drawing them out by hand on a large drawing board. The process took months, because reorganizing parts to minimize the wafer size required redrawing the circuit. Once a design was finalized, an Exacto knife was used to cut out the circuit runs and build a mask which was photo-reduced by 300x.

Because the process relied heavily on human skill and error checking, it was rare for a design to work correctly the first time, but Camenzind managed it. No doubt the combination of seeking to prove himself as a contractor and being heavily invested in his pet project caused him to be extra careful.

The Signetics 555 entered full-scale production in 1972 and became an immediate hit. Interestingly, the design wasn't patented and companies like National Semiconductor and Fairchild soon released their own versions. This helped to push the price down and ensured that the chip would become ubiquitous in the decades that followed.

Camenzind went on to have a long and successful career, but none of his subsequent designs would impact the world like his simple little timer. In fact, IEEE Spectrum named it one of 25 microchips that shook the world in their May 2009 issue.


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